At this point, Yu Xian's Heaven-Deceiving Technique advanced further, reaching the Tier 3 level.
To progress any further would require not only the reference and fusion of more secret arts, but more importantly, his cultivation realm was still too low to create even higher-tier secret arts.
A Tier 4 secret art was already at the level of a Nascent Soul True Monarch, something he could not yet aspire to.
Chapter 162